Witnesses say 26 people were killed in northeastern Borno state by attackers on horseback believed to be rebels of the Islamic extremist group Boko Haram.

Ali Abdulqasim said his home village of Kolori and the neighboring village of Baana-imam were attacked late Tuesday.

Abdulqasim said Wednesday he escaped the attack by scaling a mango tree from where he saw horsemen chase down and shoot fleeing villagers. He said he spent the night in the tree and when he came down in the morning he saw many corpses. Abbas Gava, a spokesman for a civilian defense group, said 26 people died in the attacks.

Boko Haram's six-year-old uprising has caused the deaths of an estimated 20,000 people.